Which term describes the pulling or stretching force that causes materials to extend?

• A. Gravity
• B. Tension
• C. Compression
• D. Torsion

Answer: (B)

Tension is the pulling or stretching force that tends to elongate a material. When a member is pulled along its length, the internal force within it acts to pull its ends apart, causing it to stretch. A classic example is a rope supporting a hanging weight—the rope is in tension as it is pulled upward at the top and downward at the weight, stretching slightly under the load.

Gravity is a body force that acts on masses, not the axial internal force causing extension in a member. Compression is the opposite axial force that pushes ends toward each other and shortens the member. Torsion involves twisting about the length of a member, not straight pulling or stretching.